Art and apparatus for oil well cementing



Jan. 19, 1932. c. F. LYTLE ART AND APPARATUS FOR OIL WELL CEMENTING Filed Aug. 8, 1929 gwuenlioz olLi oR GAS 0R WATER 1MPERvmus- CAP ROCK Patented Jan. 19, 1932 CHARLES F. LYTLE, OF SIOUX CITY, IOWA ART AND APPARATUS FOR OIL WEL L CEMENTING Application filed August 8, 1929. Serial No. 884,361.

This invention relates to improvements in the art of values conservation, and more particularly in the eifective cementing of oil and gas wells against loss incident to bi-lateral stray discharge or contaminationof the oil or gas from other fluids.

It has heretofore been proposed to pre vent seepage and like losses of oil and gas and the contamination of the oil and gas sands from other fluids by cementing the space between the well casing and the surrounding earth walls at the bottom of the well and upwards therefrom for a distance SllfllClQIlt to insure against oil or gas escaping from oil and gas sands into the upper strata or contaminating fluids or material finding its way from the upper stratas into the oil or gas bearing strata, but difiiculties have been encountered heretofore largely interfering with the successful cementing of the bottom portions of the well. Among these difliculties is the fact that water, mud fluid, oil and gas have mingled with, and diluted or contaminated the cement to a condition of deterioration, rendering results negative. Many attempts have been made to overcome these difliculties but such attempts have not, however, been successful or satisfactory, except under the most favorable conditions. Under the usual methods of cementing oil or gas wells, when the oil and gas is under -a heavy pressure, it will escape into and through the fresh cement before it has had a chance to harden and contaminates and keeps in motion the fresh soft cement and prevents the proper setting of cement, and thus allows the oil and gas to escape up outside of the casing into the porous stratas of the formation above, and becoming entirely lost insuch sands, or if there is water in the formation above the bottom of the casing, it will seek its way down into the oil sand and thus de stroy its value.

One of the essential objects of the present invention is the effective conservation of values, a second object the assured production of a stable and serviceable cement seal about the casing at the bottom of the well, and a third object the avoidance of gas action or other deleterious action or dilution relative to the cement.

With these and still further objects in view, the invention comprises certain novel combinations, and arrangements of parts, and certain novel steps of the art of values conservation as will in part hereinafter becom apparent and in part be stated.

In the accompanying drawing, the figure is a largely diagrammatic sectional elevation 60 of an oil and gas well and parts illustrating an embodiment of the mechanical combination comprising one phase of the present invention and facilitating the disclosure of the steps of the art comprising the balance of the 6 present invention.

As the present improved art will be more readily disclosed and understood by reference to a specific apparatus well adapted for carrying out the art, reference will be made to the accompanying drawing in detail, and the art thereafter specifically set forth.

Referring to the drawing by numerals, 1 indicates an oil or gas well broken at various points to indicate depth, which will, of course, vary according to known conditions and locality. The bottom of well 1 is shown within the oil sands 2. Well 1 is lined to the shale strata, or other appropriate depth, by pipe 3, as is usual, and as the well is shown at complete depth, a casing 4 is illustrated therein. The usual, or any well known or conventional, casing head or bradenhead 5 with a packed joint seals the space between casing 3, and easing 4, at their upper ends.

These parts are all well known and of common construction and arrangement. The upper end of easing 4 is closed by the usual cap 6, which communicates with pressure pipe line 7, such as is commonly employed for on maintaining circulation of the mud fluid in the casing. The casing head 5 is provided with the usual lateral discharge port 8 to complete the cycle, but, in this instance, a pipe 9 communicates with andfills port 8. A cook 10 is preferably provided for controlling discharge directly from pipe 9, and pipe 9 is branched at 11, and provided with a cut-ofl cook 12, a pressure gauge 13, and finally communicates with a pump, or other appropriate pressure fluid supply means 15 which is constructed to deliver through pipes 11 and 9 to well exteriorly of casing 4.

Pipe 7 is provided with an ap ro riate pressure gauge 16, and a cut-off 000 1 and communicates with a power pump 19 for receiving the mud fluid or other fluid substance (such as cement at the appropriate time).

During the operation 0 cementing the well the discharge through port 8 is allowed to escape through valve 10 while valve 12 is kept closed. The cement, which is mixed to a fluid'consistency, is then introduced and supplied from pump 19 through pipe 7 into the casin 4. The cement should be of the best quality mixed with as little water as possible to reduce it to a fluid state so that it may be readily handled by pump 19. It being previously determined what amount of cement should be utilized for successfully cementing the areas about the casing 4 above the lower end thereof, the pump 19 is operated until the entire quantity of cement has been delivered to the upper end of casing 4. The cap orv plug 6 is then temporarily disconnected and a follower plug of the ordinary type 20 introduced on top of column of cement, and cap 6 is then replaced. Pump 19 is a ain started with the supply changed to mu or other fluid, and the fluid forced into casing 4 by action of pump 19 until the cement has reached the bottom of casing 4 and all that part of said column of cement which is intended to be discharged about the bottom and up around sides of casing 4 has been thus discharged, and the follower plug 20 has reached the point in casing upon which it had been previously determined to stop the plug, which, of course, determines the amount of the cement that is left inside of the casing 4. The definite location of the plug 20 may be determined by any ordinary method, such as a measuring line, or by my improved method of metering or exactly measuring the amount offluid pumped into casing 4 after the follower plug 20 has been introduced on top of the cement. Before introducing the cement into casing 4, a slug of axle grease, or other similar material, or an ordinary disc plug is placed on the fluid to prevent any undue contamination of cement by mud, on which it is placed.

However, before the cement has reached the position just stated, and, in fact, preferably about the time when the lower end of the column of cement has reached the lower end of the casing 4, valve 10 will be slightly closed so as to create some pressure on the column of mud fluid arising outside of casing 4 by reason of the cement being forced down by pump 19. The pressure thus applied, overcomes the pressure of the oil or gas at the bottom of the hole and prevents its escape from the oil sand and contamination of the fluid cement as it passes out the bottom and up around the outside of easing 4. It also forces a portion of the mud fluid out into any porous stratas in the formation above. After the cement has reached its predetermined location in and about casing 4, the valve 10 is entirely closed and pump 15 is started, pumping fluid mud, water or other fluid through pipe 11 and valve 12 through port 8 into the space between casing 3 and easing 4. The amount of ressure supplied will, of course, be governed by the existing conditions in each" particular case, taking into consideration the porosity of stratas encountered above the oil sand, supplying such pressure and fluid as is necessary to keep the porous stratas filled with mud or other fluid, and suflicient pressure to overcome the pressure of oil and gas sand in the bottom of the well so that the oil and gas from sand at the bottom of the well will not force its way through the soft cement and contaminate and prevent the proper setting of cement.

The pressure as shown by gauge 13 is kept uniformly at a certain predetermined pressure and only such amount of fluid as is necessary to maintain that pressure is forced into the pipe by pump 15. Gauges 13 and 16 will not show the same ressure on account of the fact that the welght per cubic foot of the column of cement outside of casing 4 is heavier than the weight of the mud or other fluid forced inside of casing 3 to push the cement to its required location. Valve 17 may be closed and kept closed after the cement has been pumped to the proper predetermined location and all necessary pressure applied to pump 15 through the exterior of casing 4. The pressure from pump 15 is constantly exerted so as to maintain a uniform redetermined pressure on gauge 13, thus e ectively preventing the possibility of gas agitation or other deleterious action or contaminating element percolatin or otherwise finding its way up through t e cement, or alongside of cement in contact with walls with which cement impinges, and allowing the cement to set under pressure without movement, agitation or contamination. It is well known that cement which has set under pressure, attains 'a greater degree of hardness and strength than cement setting without pressure.

Thus, the well is cemented off with absolute assurance of a perfect seal both against escape of oil and gas from the oil sands 2 up into the porous higher stratas and against contamination of objectionable descending substances.

After the cement has effectively set, cap 6 is removed and the plug of cement in bottom of easing 4 drilled out inthe usual manner.

In the process of cementing the well, in accordance with my invention, I take into consideration the tendency of the formation at the top of the column of cement of laitance, which, owing to its lighter specific gravity, floats towards the top of the body of cement. This substance, while apparently cement-like, is extremely weak in bond so that unless it is taken into consideration, it is likely to prevent the successful cementing of the well in case the cement should be forced down too far in the casing 4 and laitance instead of good cement be around the bottom of casing 4, in which case it would prevent the successful cementing of the well. In other words, by calculating the possible amount of laitance, which may develop, and taking into consideration that the more water that is used in mixing cement, the greater percentage of laitance will develop, I move the cement column down the well casing only to such point as will leave a portion of the pure cement in the casing with laitance cement superimposed upon the same.

So far as I am aware, it has never been proposed heretofore to close off or seal the space between the well casing and the surroundin wall or outer casing at the top thereof uring the process of cementing the well so as to obtain the counterbalancing pressures, and I desire -it to be understood that I consider this step of my method to be broadly new and my claims therefor entitled to broad interpretation.

What is claimed is 1. In the art of cementing wells, embodying a well casing, emplacing cement exteriorly of the well casing, closing the well'to atmosphere, and producing opposed artificial pressure forces between which the cement is confined to maintain it in a state of quiescence for facilitating its setting.

2. In the art of cementing wells, introducing cement into a well, introducing fluid under pressure above the cement, and continuing the introduction of such fluid under pressure sufliciently for insuring location of the cement in the predetermined required position at the bottom of the well, and introducing a counterbalancing pressure opposing the pressure of said pressure fluid and allowing the cement 'to set while subjected to the counterbalancing pressures.

3. In the art of cementing wells, introducing cement into the casing of a well, forcing the cement down the casing to a predetermined relation at the bottom of the casing, and introducing a counterbalancing pressure exteriorly of the casing.

4. In the art of cementing wells, introducing cement into the casing of a well, forcing the cement down the casing to a predetermined relation at the bottom of the casing,

introducing a counterbalancing pressure exteriorly of the casing, and maintaining the opposing pressures while allowing the cement to set. 1%

5. In the art of cementing wells, introducing cement into the casing of a well, forcing the cement down the casing to'a predetermined relation at the bottom of the easing, introducing a counterbalancing pressure exteriorily of the casing, maintaining said opposing pressures sufficiently unequal to allow the cement to descend within the casing and pass through the bottom thereof about the exterior of the casing, and increasing the counterbalancing pressure exteriorly of the casing to complete equalization with the interior pressure as the cement reaches balancing pressure exteriorly of the casing to complete equalization with the interior pressure as the cement reaches the location for setting, and maintainingthe equallzed pressures while allowing the cement to set.

7. In the art of cementing wells, bringing cement to the required location at the bottom of the well under differential pressures at the opposite ends of the column of cement, and equalizing the pressures as the cement reaches the final location by raising the lower pressure. a

8. In the art of cementing wells, delivering cement to the bottom of the casing of a well, and passing cement upwardly about the exterior of the casing and establishing a counterbalancing resisting pressure on 'topof the column of cement exteriorly of the casmg 9. In well apparatus, the combination, w1th a well and a casing therefor, of means for forcing cement to the bottom of a well through the casing and upwardly about the end thereof, and means for introducing a counterbalancing pressure in a direction opposing the movement of the cement to comress the cementitious material and to subect the cement to opposing pressures prlor to and during setting.

'10. In well apparatus, the combinatlon, with, a well having a casmg, of oement supplying means, means for introducing pressure fluid to the casing to act on cement delivered from said supply means for forcing cement down the casing and through the bottom end of the casing and upwardly about the exterior of the casing, and means for sealing off and introducing pressure flui'd to the exterlor of the casing for resisting the pressure of the interior pressure fluid to, thereby act on the cement supplied to maintain it quiescent for settin v 11. Ihe process ,of cementing wells which includes the steps of introducing cement into the s ace between the well casin and surroun ing earth strata, then co the cement between two opposing fluid Pressure heads tohold it quiescent while settmg and regulating one of said pressure heads to compensate for leakage losses within the well.

In testimony whereof I affix my si ature.

CHARLES F. L TLE. 

